You can only enter one instructor per training and instructor is selected when you Add Event.
Jump to (02:40 minutes) for instructions on how to Add Event.
Jump to (04:15 minutes) to see where to enter approved instructor.
Your instructors will request access to be trainers for your Training Organization from the "Request Instructor Access" (click for instructions) on the left hand tool bar.
Jump to (01:41 minutes) for instructions on being an Instructor.